Stranded Wire Gauge Chart

Same copper, different construction

Gauge describes copper cross-section, not outside diameter. Stranded classes (Classification 1 to Class H workmanship beyond braid) change the outer diameter for the same electrical rating: more, finer strands create higher flexibility with more air gaps inside. That's why your calipers on a multi-strand bundle always read "one size up".

Where stranded wins

• Vibration: Solid work-hardens and fatigues at terminations; stranded flexes thousands of times without cracking the strand at the crimp line.
• Pushing through conduit: Fine-strand (Class K) cable is floppier and snags less on long conduit runs.
• Terminals: Lugs and compression terminals are designed for stranded cross-section; solid wire under a set-screw lug on a vibrating machine works loose.

Where solid wins

House branch wiring sticks with solid because straight conductor sits firm in duplex outlets, dip mitigated, and any strand that rushes into the wrong pole looks identical from the front but ages differently — field-standard solid keeps residential terminations inspectable.

Stranded wire gauge chart: kinds, classes and sheets

Stranded wire is gauged by copper area, not jacket size: a 12 AWG stranded bundle carries equal copper to 12 AWG solid and usually reads wider outside. The strand classes borrow different flex histories: Class B (7 strands for smaller sizes, 19 for larger) is the default power and grounding class; Class K welding cable uses hundreds of fine strands for the extreme flex; audio and test-lead classes (16-30 AWG tinned) favor solderability over flex life. The commonest real question — "is my skinny 19-strand cable really 12 AWG?" — ends the same each time: total strand area decides, not outside width, and the table above resolves the match from a caliper measurement.

Terminations: ferrules, lugs and the spring-clamp trap

Fine strands misbehave in the clamps that were designed for solid wire. Screw terminals (the kind on older panel boxes and budget DIN blocks) need ferrules on flexing strand or they splay and creep loose months later. Spring-terminal blocks (Wago-style) are strand-friendly by design up to their rated wire; bigger power landings want compression lugs crimped with the marked die. Two failure patterns worth remembering: nicked strands from over-stripping become fatigue points, and a bundle trimmed back "to fit" surrenders the cross-section that the amp rating relied on — re-terminate, don't trim. Fixed house wire never faces this because it uses solid; every vehicle, appliance and portable cord does, which is why the automotive chart publishes chassis-safe strand picks.

When strand count wins the job

Choose stranded when the wire lives with motion: speaker feeds that move behind stands (here the speaker wire gauge chart doubles as the pick list), battery cables that vibrate for a decade, robotics umbilicals and door cords. Choose solid when the wire is the structure: in-wall runs, breadboard jumpers, and anything pushed through a conduit once. Money note for budget builds: doubling parallel conductors halves resistance — two 16 AWG strands in parallel equal one 13 AWG breather, a trick used in DC banks (keep each pair length-matched) and documented in the table above at every size that carries a real current rating. Stranded is also the only sensible choice below 26 AWG, where solid wire snaps under a crimp tool.